Use Two digital pots in 1 IC at different voltages

[Willemg12]

To do a modernization of an old lab supply I want to replace the old pots with digital potentiometers.
TI and Linear Technology have good choices in that.
I want to steer these over SPI/I2C. The problem I face is that the digital potentiometer ICs cannot be used out of the rail to rail voltages. E.g. 0V-5V

Where I want to be one at the GND and the other at the VCC level. +24V

UPDATE. In the figure a schematic is shown with the two pots in.

So as this is out of spec for most ICs
what could be a solution for this?

Thank you

[Benta]

I'd check ON Semiconductor. ON acquired Catalyst, who were famous for their digital pots.

[Willemg12]

I did. ON has a pot that has Vh up to 16 V.
But in my case that will be not enough, as i work with 24 volts.

Should i use extra Elements..
Dunno...

[tszaboo]

Some AD parts, like AD7376 goes up to 30V. They dont work outside the suply rails, because they have FETs built in, switching stuff.

[Howardlong]

Microchip MCP41HV31/51 for SPI, MCP45HV31/51 for I2C, but they are only single pot per package. Up to 36V, or +/-18V.

[Zero999]

The schematics don't look right. Are they direct extracts from the service manual or the product of reverse engineering?

Is it not possible to use a DAC and suitable amplifier? Normally the voltage and current limits are controlled by a reference which is set by potentiometers. You can probably replace the potentiometers with voltage sources.

[Willemg12]

Thanks hero999 and all others

You were right. At first the only thing that i wanted was a direct change from analog to digital.

I included the schematic of my trustworthy old bench supply.

The pot P2 is easily interchangable (though i not favor the value of 1k)  But what about P1....
Geven the fact that i want one uP control the device ...

[Benta]

Something's still wrong... the power stage has no base drive. Scratch that, I just untangled the 723 ground connection.